Choose 1 real solution between 4 solutions

hello, i have a probleme of making Ma choose the right answer, the right solution is the 2nd one of x, y and z, is there any command to do that??

Answer 1

[Rik]

You're using a syntax that is no longer valid in Matlab. Since you didn't specify your Matlab release (and posted your code as picture) I can't confirm the code below will work for you. It is also unclear to me why the first solution of you picture isn't a valid solution.

syms x
x=solve(x^3==1)

x = 

result=double(x);
L=abs(imag(result))<=eps;
correct_result=result(L);
correct_result

correct_result = 1

[maze djenn]

I use 2010 version. I choosed the 2nd question because it's the value that seems logic, im stimulating the heat transfert in solar heat collector and those solutions are the temperatures in Kelvin

[Rik]

Then the code I showed you should solve your question.

Just a slight edit to L (and to the syntax for solve to account for your release):

syms x
x=solve('x^3=1');
result=double(x);
L= ... list all conditions here
    abs(imag(result))<=eps & ...
    real(result)>0;
correct_result=result(L);
correct_result

You should really mention it if you're using something older than a few years. R2010a and R2010b are not trivial to get to run on a modern operating system.